The invention is directed to a pressing tool for pressing a cylindrical pressing member or a pressing member comprising a cylindrical portion onto a round profile, particularly a pipe conduit, comprising a plurality of press dies for pressing the pressing member onto the round profile from all sides in a pressing process, and further comprising a plurality of holding members provided with receiving portions for holding the press dies, at least one of said holding members being adapted to be moved towards the other holding member(s) and away therefrom, respectively.
Pressing tools of the above type are used for establishing press connections between pipe conduits and connector pieces, so-called fittings, for connecting cable shoes or connectors to conductors (full profiles) and for similar uses. The term "round profile" as used throughout this application is meant to cover both hollow profiles and full profiles. A full profile, for instance, can also be a wire rope.
For connecting a round profile by pressing action to a connector piece of a random type, e.g. to a cable shoe, a cable connector or a pipe conduit fitting, a substantially cylindrical pressing member is pressed onto the round profile. In a connection for a pipe conduit, the pressing member can be e.g. a pressing shell enclosing the pipe conduit. In a cable connector, the cable connector itself serves as a pressing member; in a cable shoe, the cylindrical portion thereof, provided for receiving the end of the cable, constitutes the pressing member. The pressing tools utilized for effecting the press connection, being pressing pliers or pressing tools to be driven hydraulically or by a motor, comprise a plurality of press dies for pressing the pressing member onto the round profile from all sides in a pressing process. In case of a hexagonal pressing tool, for instance, two pressing dies are provided. Normally, the pressing dies are fastened on two holding members provided with receiving portions for holding the press dies. In pressing pliers, the two arms of the pliers form the holding members for holding the press dies; in a pressing tool having one holding member to be displaced in linear fashion, this holding member is provided as a longitudinally displaceable slider adapted for movement towards a usually bracket-like holding member and away therefrom.
The pliers known from DE 91 03 264.4 U1, designed for establishing pipe connections by pressing action, are provided with three press dies. Two of these press dies are supported on the arms of the pliers while the third press die is arranged in stationary manner between the arms of the pliers. The arms of the pliers are pivotable about rotational axes extending in parallel to each other, wherein, when the pressing pliers are closed, the two press dies arranged on the arms of the pliers move towards each other and in the direction of the stationary press die, while in their final pressing position they are arraged in mutual abutment and form a ring enclosing the pressing member. Since, during the closing of the pressing pliers, the movement of the press dies does not progress radially but--because of the pivoting of the arms of the pliers about the rotational axes--along an arc in the direction of the pressing member, the pressing effect is not yet optimal. Especially for the pressing of ends of pipe conduits onto fittings, high demands are posed to the tightness of the connection. These high demands regarding the tightness of the pipe connection cannot be met even by hexagonal pressing tools (no matter whether they are operated hydraulically or manually). The two press dies of a hexagonal pressing tool have different pressing faces so that the pressing has a slightly oval configuration. Also a hexagonal pressing tool suffers from the problem that those pressing faces which do not extend transversely to the moving direction of the press dies, do not move toward the pressing member in radial manner.